I wonder if these findings will hold as others look at the data and other questions are asked.

…a new study out of University of Colorado Denver and Montana State University shows that legalizing medical marijuana sales in various states over the past two decades has led to a nearly 10 percent drop in traffic fatalities. What the study really shows–by way of causal chain–is a five percent drop in beer sales, and that has in turn led to fewer fatalities on the road.

…

They found several connections and trends that seemingly stem from the legalization laws, but most notably they found evidence that alcohol consumption by 20- to 29-year-olds decreased, and that translated into fewer deaths on the road. Previous simulator studies have shown that drinkers tend to drive more aggressively and take more risks, while marijuana users tilt toward risk-averse behaviors.

I have to admit that I’m always a little skeptical of researchers who characterize opposition as fearing social and gateway effects (The most damning framing—reflexive, anti-intellectual and moral alarmism.) and present supporters as primarily concerned about medical treatment. (A pretty generous characterization—ignoring the marketing and cultural elements that make is clear that a very substantial number of users are not really using it to treat medical problems.)

However, I find the possible relationship between legalization and alcohol consumption to be interesting.